Synergistic effect of glucose and glycerol accelerates microbial lipid production from low-cost substrates by Cutaneotrichosporon oleaginosum

Efficient conversion of various low-cost substrates into lipid is pivotal for better techno-economics of the microbial lipid technology. In this study, lipid production by Cutaneotrichosporon oleaginosum from glucose, glycerol, and their mixture at various mass ratios was investigated. Co-existence of glucose and glycerol rendered higher lipid productivity and yield, supporting synergetic effects of the two agents. Interestingly, the theoretical lipid yield was not improved through combination utilization of glucose and glycerol based on the prediction using a small-scale metabolic model. The synergy was probably owing to the improvement of substrate transportation efficiency through simultaneous assimilation of glucose and glycerol. When waste paper enzymatic hydrolysates and crude glycerol were co-utilized, lipid content, yield, and productivity attained 62.3%, 18.9 g/100 g, and 4.1 g/L/d, separately. The lipid samples showed fatty acid compositions comparable to that of rapeseed oil. The prediction of biodiesel properties demonstrated the feasibility for high-quality fuel production. These results showed that the co-fermentation strategy could serve as an efficient way to advance microbial lipid production, which has bright prospects expanding to low-cost substrates including cellulosic biomass and crude glycerol.